Police say Gayle and Sheila Muhs could face murder charges after they opened fire on two vehicles last week, killing a 7-year-old boy.

ABC News

Gayle and Sheila Muhs gave trespassers a blunt warning. They posted a large sign outside their Texas home saying trespassers would be shot and survivors would be shot again.

They weren't joking.

The Muhs are currently being held on charges of aggravated assault for allegedly firing at least two shotgun blasts at a pair of packed cars that stopped outside their rural Texas house. Those charges are expected to be upgraded to murder, since a 7-year-old boy who was wounded in the assault has died from shotgun pellets to his head and face.

But police said the families in the two cars were driving on a public road when the Muhs opened fire from their house, killing Donald Coffey Jr. and hitting three others, including the boy's 5-year-old sister.

Outside the Muhs' house is a handpainted sign complete with misspelling and exclamation points that warns: "Trespassers Will Be Shot. Survivers Will Be Reshot!! Smile I Will."

Police got a 911 call just after 9 p.m. Thursday, DeFoor said, from Sheila Muhs who "reported there were people in jacked up four-wheel automobiles ... and that she shot them." She also reported that the vehicles were destroying the nearby levees.

But in reality, DeFoor said, the families in the two cars had done nothing illegal. And, he said, they never set foot on the Muhs' property.

DeFoor said the Coffey family -- mom Becky, dad Donald Sr. and their three children -- were visiting friends along with Patrick Cammack and Cindy Nelton in the Muhs' neighborhood near Dayton, Texas, about 45 miles east of Houston.

The two families had planned to go off-roading at the nearby government-owned levees on the way home, an activity that is both popular and legal in the area, DeFoor said.

In the Jeep were Cammack, 30, Donald Coffey, 30 and Donald Jr., 7. In the following Ford SUV were Becky Coffey, Nelton and the Coffey's 5-year-old daughter, Destiny, and 11-year-old son.

The two cars stopped on the county-owned road outside the Muhs' home so one of the boys could go to the bathroom by the side of the road.

That's when, DeFoor said, the couple ran out of their house.

"Sheila Muhs started cursing at them 'Get off our property,'" DeFoor said and fired off at least one round, causing the Jeep, which had started to leave, to veer off the road.

Muhs, he said, then put the shotgun down and chased after the Jeep on her all-terrain vehicle, eventually catching up to it on the levee about 100 yards away, the ATVs headlights pointed at the Jeep.

While that was happening, DeFoor said Gayle Muhs picked up the discarded shotgun and fired at the SUV. DeFoor said the trajectory of that shot showed that the back of the SUV was sprayed with pellets, it's rear window blown out.

"The SUV was in the process to flee," the officer said.

Nelton told the Houston Chronicle that they yelled at the Muhs after the first shot that they had kids in the car and to stop shooting, but another gunshot -- possibly more -- is all they heard in return.

Nelton said Destiny was in the back of the SUV screaming.

"She said, 'Mama, they shot me. Mommy, they shot me.' There was blood all over her," Nelton told the Houston Chronicle.